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一種兼顧影像壓縮與資訊隱藏之技術

This paper presents a novel information hiding scheme based on switching-tree coding, allowing the embedding of a large amount of information in the index table with minimal additional bits. Experimental results demonstrate the effectiveness and efficiency of the proposed scheme.

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一種兼顧影像壓縮與資訊隱藏之技術

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  1. 一種兼顧影像壓縮與資訊隱藏之技術 張 真 誠 國立中正大學資訊工程學系 講座教授 http://www.cs.ccu.edu.tw/~ccc http://filter.cs.ccu.edu.tw

  2. Outline • Search order coding (SOC) • Switching tree coding (STC) • Experimental results • Conclusions

  3. Search-Order Coding (SOC)

  4. An example for indices of VQ

  5. Search-Order Coding (SOC) Searched point Non-searched point

  6. Search-Order Coding (SOC) Indicator The compressing steps P1 = 1 00011111 P2 = 1 11001111 P3 = 0 00 … P6 = 0 01 Compression codes = 100011111 111001111 000 …

  7. Information hiding on the SOC codes • The proposed scheme: - Information hiding: to embed secret data into host image - Steganography : to embed secret data into host image and the interceptors will not notice the existence of secret data - Based on SOC

  8. OIV (original index value) Information hiding on the SOC codes • Main idea: Ex. receiver receives the compression codes : 010101101110110110011000011 SOC OIV SOC SOC It means that the embedded secret data is “01100” if SOC is represented to hide “0” and OIV is represented to hide “1”.

  9. Information hiding on the SOC codes • Method: ex. A 3*3 index table: If the secret data is “111110100”, then the hiding position of each bit will be in the raster scan order.

  10. hide “0” SOC ====> there is nothing that needs to change for its compression codes hide “1” SOC ====> translate SOC into OIV (give up SOC coding and keep the OIV) hide “1” OIV ====> there is nothing that needs to change hide “0” OIV ====> translate OIV into SOC ex. 11 (SOC) Information hiding on the SOC codes Defined: “0”  embedded into SOC and “1”  embedded into OIV. • Embedding phase: + OIV

  11. compression codes are still OIV: 100010010 translate SOC into OIV : 000 => 100011110 translate OIV into SOC : 100100000 => 01100100000 Information hiding on the SOC codes • Ex.

  12. Information hiding on the SOC codes • Cost table (bits):

  13. Information hiding on the SOC codes • Security: For enhancing the security of our method, the position in the index table for hiding each bit of secret data can be determined by using pseudo random number generator, and the secret data can be encrypted by using traditional cryptography system such as DES or RSA in advance.

  14. Experimental results

  15. Experimental results

  16. Experimental results

  17. Experimental results

  18. Switching tree coding (STC)

  19. Switching-tree coding (STC) • Sheu proposed the STC algorithm in 1999 • Re-encode the index table U L the current index

  20. Switching-tree coding (STC) • If P = 7, then P = U • P’ = ‘11’ P=(U or L) or P=A P=(U or L) • If P = 10, then P = L • P’ = ‘10’

  21. P=(U or L) or P=A 16 P=(U or L) • If P = 14, then P = A in index (3) • P’ = ‘01’ || index (3) = ‘0100011’ • If P = 17, then • P’ = ‘00’ || (17) = ‘0000010001’ n=5

  22. Information Hiding on the STC codes (IHSTC)

  23. Information Hiding on the STC codes (IHSTC) • Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … Index table 40 72

  24. P’ = ‘00’||(40) ‘00’||(25) ‘00’||(21) … ‘00’||(17) ‘10’ Information Hiding on the STC codes (IHSTC) • Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P=(U or L) or P=A 40 72 P=(U or L)

  25. Information Hiding on the STC codes (IHSTC) • Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P=(U or L) or P=A 40 72 P=(U or L) P’ = ‘00’||(40) ‘00’||(25) ‘00’||(21) … ‘00’||(17) ’10’

  26. Information Hiding on the STC codes (IHSTC) • Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P=(U or L) or P=A 40 72 P=(U or L) P’ = ‘00’||(10) ‘00’||(25) ‘00’||(21) … ‘00’||(17) ‘00’||(100) ‘10’‘00’||(128) …

  27. Information Hiding on the STC codes (IHSTC) • Watermark: 0 1 0 0 1 1 0 0 0 1 1 0 1 0 … P=(U or L) or P=A 40 72 P=(U or L) P’ = ‘00’||(10) ‘00’||(25) ‘00’||(21) … ‘00’||(17) ‘00’||(100) ‘10’‘00’||(128) … ‘11’

  28. Three binary connection tree P=U or P=(L or A) P=L or P=(U or A) P=(U or L) or P=A P=(U or A) P=(L or A) P=(U or L)

  29. Three binary connection tree • If U’s freq. > L’s freq. • Tree C • If U’s freq. < L’s freq. • Tree B • Otherwise Tree A Tree B Tree C

  30. Experiment results Image size = 512*512, n = 3 and |H| = 1024 NSTC: 在 index table 中，可藏入之index數 |H|: Secret Information 之長度 Difference: 藏入前與藏入後 bit 數的差異

  31. Experiment results Image size = 512*512, n = 3 and |H| = 2048 Image size = 512*512, n = 3 and |H| = NSTC

  32. Image size = 512*512, n = 5 and |H| = 1024 Image size = 512*512, n = 5 and |H| = 2048 Image size = 512*512, n = 5 and |H| = NSTC

  33. Conclusions • A novel information-hiding scheme based on a switching-tree coding • The IHSTC system can hide a huge amount of information in the index table • Only a few extra bits are needed to record the corresponding information • The average time needed to hide an information character is 0.077seconds • IHSTC -- an efficient and effective scheme for hiding secret information

  34. Questions ??

  35. Thank You !!

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